The guy that did the interior on our Scout also does the same work on RV's, so we let him do it.
They will remove all the seats and the couch since they are going to recover them, but even if we were just going to change the carpet, all that stuff would have to be taken out since it is bolted to the floor. There is also a small amount of carpet around the bed.
He prefers installing it himself to make sure it turns out right while all the stuff is removed (it has to run up under the dash in the driver's area) and to remove the old carpet, install the new (including the step side pieces and trim was +/-$600. The cost of the carpet was about $400 (almost 20 yards @ $20/yd.)
We are going with ultra leather and memory foam for the front seats and the chairs across from the couch. I will try to get some progress photos to show the process. We are trying to find someone to put the wallpaper in today. Seems the local wallpaper shops don't do RV's. Go figure.
And I won't wallpaper with my wife. We did it once and our marriage barely survived.